Are you going with a natural wood for baseboards, Staining & finishing them? or are you going to paint them? if your going to paint them save yourself some $$ and go with MDF baseboards. no need for real wood if your going to paint them. MDF is usualy 1/4 the price of wood.
Here is further explination on the MDF Baseboard.
http://www.burtonmoldings.com/basebo...f-molding.aspx
the "green" drywall is moisture resistant. This is used in areas such as showers & Bath tubs. the regular drywall will fall apart if it gets wet regularly.